Encapsulation resins

ABSTRACT

Curable polyorganosiloxanes are provided that cure in the absence of a hydrosilylation catalyst. The cured polyorganosiloxanes have increased stability and can be used as encapsulation resin is at a temperature far lower than 300° C., have excellent light transmission properties (colorless transparency) in a wavelength region of from ultraviolet light to visible light, light resistance, heat resistance, resistance to moist heat and UV resistance, and do not generate cracks and peeling even in use over a long period of time.

FIELD OF THE INVENTION

The present invention relates to encapsulating materials preferably usedin the fields of semiconductor luminescent devices and aerospace. Morespecifically, the invention relates to curable polyorganosiloxanes thatcure in the absence of a hydrosilylation catalyst, and which when curedshow excellent heat resistance and UV resistance performance.

BACKGROUND OF THE INVENTION

High brightness light emitting diodes (HBLEDs) offer enhanced energyefficiency thus making them suitable for specialty lightingapplications. An LED device is usually composed of the LED chipfabricated onto a substrate and then encapsulated by a material actingas a lens. The following are the operational requirements of a materialto be utilized as an encapsulant of LEDs: optical clarity, hightemperature resistant, UV resistant, high refractive index and variablemechanical properties (preferably soft to hard materials).

Encapsulant materials must be optically transparent (greater than 90%transmittance) and should be able to withstand high temperatures, forextended periods of time, without degradation in mechanical and opticalperformance. The LED device encounters high temperature conditionsduring the device fabrication (soldering up to 260° C.) and during theactual device operation (around 150° C. for thousands of hours).

Epoxy resins have conventionally been used as a transparent resin forthe encapsulation (1, 2). Also, PMMA (polymethylmethacrylate-PMMA),polycarbonate, and optical nylon have been used. However, opticalproperties of such conventional resins degrade over time. Coloration, or“yellowing”, occurs either by heat induced degradation (heat resistance)or via prolonged irradiation with short wavelength light(ultraviolet-resistance). This results in water entering from theencapsulated portion to disturb performance of LED, and the resindiscolors by ultraviolet light emitted from LED to decrease lighttransmittance of the transparently encapsulated portion. Mechanicaldegradation of the encapsulant also results in cracking, shrinking ordelamination from the substrate. Thus, it is desirable to have anencapsulant system that allows variation of mechanical properties, fromsoft elastomers to hard plastics. The encapsulant must be hard enough toserve as mechanical support for the LED component, and at the same timemust be soft or flexible enough to relieve internal stress during thedevice fabrication (prevent damage to LED chip or wires) and duringtemperature cycling (expansion and contraction of materials withdifferent thermal expansion coefficients).

To overcome the above problems, a fluorine-containing cured product intransparent encapsulation of an emission element has been proposed (3).Although, this fluorine-containing cured product has excellent colorlesstransparency, light resistance and heat resistance as compared with theepoxy resin, but has the problem that adhesion to a material to beencapsulated is poor, and it is liable to peel from the material to beencapsulated. Furthermore, a material of LED chip, specifically amaterial of an emission layer of LED chip, has high refractive index,specifically refractive index of light in a visible light region, offrom 2.5 to 3.0, but the fluorine-containing cured product has lowrefractive index of light in the same wavelength region. Therefore, thepick-up efficiency of light in the same wavelength region has not alwaysbeen sufficient in the fluorine-containing cured product.

To solve the above problems, LED encapsulated with a glass prepared witha sol-gel method were proposed (4). This LED makes it possible to reducehygroscopicity through an encapsulating material and decrease in lighttransmission due to discoloration of an encapsulating material, andadditionally improve heat resistance. However, in the sol-gel glass,fine pores are liable to remain and cracks are easily generated.

Therefore, there was the problem that when water enters the fine poresor crack sites, the water disturbs performance of LED. Furthermore, aglass is generally poor in adhesion between a substrate and a wiringmetal as compared with a resin. Therefore, there was the problem thatwater enters from the interface between an encapsulating glass and thesubstrate or the wiring metal.

It has also been proposed that a low melting glass is heat melted, andLED is transparently encapsulated with the melt (5). However, where alow melting glass is generally heat melted, it is necessary to heat theglass to a temperature of from 400 to 700° C. Therefore, a phosphor usedin LED may undergo heat deterioration.

To those problems, a silicone resin (polyorganosiloxane) havingexcellent heat resistance and ultraviolet resistance is used as asubstitute of the epoxy resin. However, silicone resins up to now tendto scar easily, and are not yet sufficient in adhesion, colorlesstransparency, heat resistance, resistance to moist heat and UVresistance (5, 6, 7, 8, 9).

With the recent development of GaN-based devices which emit shortwavelength radiation such as blue light or ultraviolet light, andsubsequently white light by combining these light emitting diodes with afluorescent phosphor, the material requirements for the encapsulant hassignificantly increased. Materials should be able to withstand exposureto radiation of high intensity without degradation in optical andmechanical properties.

Therefore, there is a need for robust LED encapsulants with superioroptical clarity, high temperature-resistance, UV-resistance, highrefractive index, and with variable elastic properties (preferably softto hard materials). The present invention allows such properties to beachieved. There is also a need for LED encapsulants with varyingmechanical properties, without sacrificing their optical clarity, hightemperature-resistance and UV-resistance. The present invention allowssuch properties to be achieved.

SUMMARY OF THE INVENTION

The present invention provides curable polyorganosiloxane that can beused in encapsulation at a temperature far lower than 300° C., hasexcellent light transmission properties (colorless transparency) in awavelength region of from ultraviolet light to visible light, lightresistance, heat resistance, resistance to moist heat and UV resistance,and does not generate cracks and peeling even in use over a long periodof time. In this respect, the term “colorless transparency” means totransmit light having a wavelength region (350 to 800 nm) of from nearultraviolet light to visible light, and means that light transmittanceof a cured film (thickness: at least 100 um) in such a wavelength regionis preferably 80% or more, and more preferably 90% or more.

The invention also provides for encapsulating materials using thecurable polyorganosiloxane, and materials for the aerospace industryutilizing the excellent properties of the disclosed curablepolyorganosiloxane in order to overcome the above-described problems inthe prior art.

The polyorganosiloxanes of the invention may be used alone, or may beused as a composite with other material. For example, as a material foraerospace industry, the polyorganosiloxane is combined with acarbon-based nanomaterial to form a composite, and such a composite canbe used as a material for removing static electricity, a conductiveadhesive, a gasket material, a flash defensive material, anelectromagnetic shielding material, a tank material, a rocket outermaterial and the like.

The invention provides for curable polyorganosiloxanes comprising acompound represented by the following formula in an amount of 50% byweight or more, characterized in that said polyorganosiloxane cures,substantially in the absence of a hydrosilylation catalyst:

-   -   wherein R₁ to R₁₀ each independently represent a group selected        from hydride, alkyl, alkenyl, aryl and non-condensable silyl        group, and m and n each are an integer of 0 or more.

In another embodiment, curing of such curable polyorganosiloxanes canoccur by heating at a temperature of 80° C. or higher for an overallheating temperature of 1 hour or more. Alternatively, such curablepolyorganosiloxanes can be cured by methods known to those of skill inthe art such as, but not limited to, using UV radiation.

In another embodiment, a method is provided for producing a curablepolyorganosiloxane, by reacting a vinyl-containing compound (A) and ahydrosilyl-containing compound (B), where said compounds A and B arerepresented by the following general formulae:

-   -   wherein R₁₁ is a group selected from alkyl, aryl and        non-condensable silyl group;

wherein R₁₂ to R₂₀ each independently represent a group selected fromhydride, alkyl, alkenyl, aryl and non-condensable silyl group, and m andn each are an integer of 0 or more.

In yet another embodiment, the aforementioned vinyl-containing compound(A) and/or the hydrosilyl-containing compound (B) have a weight averagemolecular weight of 3,000 or more obtained by measuring with GPC (gelpermeation chromatography) using a polystyrene standard material incalibration curve measurement.

In a preferred embodiment of the invention, the curablepolyorganosiloxanes are obtained using a noble metal oxide as acatalyst.

In yet another embodiment, silicone members are provided by curing thecurable compositions of the above invention. The silicone membersdisclosed can be used in semiconductor luminescent devices or in devicesused within the aerospace industry.

In one embodiment, a curable composition comprised of the curablepolyorganosiloxanes may contain solvents, adhesion promoters (e.g. epoxycontaining material), and/or filler-like materials (e.g. silica-gel ornano sized carbon) known to those of skill in the art.

As a result of extensive and intensive investigations, it has been foundthat according to a specific method for producing a curablepolyorganosiloxane, a polyorganosiloxane capable of satisfying the aboveobjects can be obtained. Additionally, the use of solid metal noblecatalysts in the present invention means that, because they can easilyremoved from the reaction products, substantially less catalyst residueis present in the curable polyorganosiloxane compared to when usingconventional methods that rely on fixed supported catalyst. As a result,undesirable side-reactions, originating from the presence of suchcatalyst residue, are reduced. This contributes to markedly improvestorage stability of a polyorganosiloxane product.

It has been further found that a noble metal oxide catalyst separatelyrecovered can be reused, which is a preferred system industrially andeconomically.

The invention also allows for the mechanical properties of theelastomeric resins to be varied and/or tuned to the desired stiffness,toughness and flexibility that best suit the specific application. Thesystem offers a range of material platforms that fulfill all of therequirements and function as advanced encapsulating materials for bothLED devices, as well as other emerging applications.

The polyorganosiloxanes of the invention are suitable for use not onlyin the LED field, but as materials for the aerospace industry thatrequires various properties such as light transmission properties(colorless transparency), light resistance, heat resistance, resistanceto moist heat and UV resistance, and other materials.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, reference isnow made to the following descriptions taken in conjunction with theaccompanying figures, in which:

FIG. 1 shows a flow chart that represents the general procedure for thepreparation of the functionalized PDMS-based encapsulants with highmolecular weight vinyl silane.

FIG. 2 gives the molecular structures of the different high MW vinylsilanes used.

FIG. 3 shows a graph that compares the optical transmission before andafter thermal ageing at 200° C. for 1 week of the formulation containinga high MW vinyl silane (MT) given in Example 1 of this invention.

FIG. 4 shows stress-strain isotherms of the formulations using MT vinylsilane, prepared with and without solvent, as given in Example 1 of thisinvention.

FIG. 5 shows stress-strain isotherms of the formulation containing highMW vinyl silanes given in Example 1 and Example 2 of this invention.

FIG. 6 shows a table disclosing the properties of resins made withnon-condensable reactants compared to those made with condensablereactants.

FIG. 7 shows a table disclosing the properties of phosphor pastes madefrom curable compositions of the invention compared to those the priorart.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates silicone resins that can be cured by heat in theabsence of a hydrosilylation catalyst. Silicone resins produced by theabove method have excellent adhesion, transparency, resistance to moistheat and UV resistance, and are therefore useful in various applicationssuch as an encapsulation resin of LED, a phosphor paste and an aerospacematerial.

Novel curable polyorganosiloxanes are provided having the generalformula of:

where R₁ to R₁₀ each independently represent a group selected fromhydride, alkyl, alkenyl, aryl, and non-condensable silyl group, and mand n each are an integer of 0 or more.

Preferred specific examples of the above general formula in thespecification are as follows:

The alkyl, alkenyl, aryl, and non-condensable silyl group may besubstituted with a halogen atom. Examples of the preferred alkyl includemethyl, ethyl, propyl and trifluoropropyl. An example of the preferredalkenyl includes vinyl. An example of the preferred aryl includesphenyl. An example of a preferred non-condensable group includetrimethylsilyl, triethylsilyl and triphenylsilyl groups.

Curable polyorganosiloxanes are provided by reacting a vinyl-containingcompound A, represented by the following general formula, and ahydrosilyl-containing compound B, represented by the general formula:

wherein R₁₁ is a group selected from alkyl, aryl and non-condensablesilyl group;

where R₁₂ to R₂₀ each independently represent a group selected fromhydride, alkyl, alkenyl, aryl and non-condensable silyl group, and m andn each are an integer of 0 or more.

The above vinyl-containing compound A preferably contains a compoundhaving 4 or less, preferably 3 or less and more preferably 2 or lessvinyl groups in one molecule in a proportion of 50 mol % or more fromthe standpoint of cost and general-purpose properties. From thestandpoint of increasing the degree of crosslinking and improvingphysical strength of a cured product, a compound having a structure thatsiloxane high molecular chains are extended to at least three directionswith a center on its optional silicon atom is also preferred.Specifically, compounds generally called T-type silicone resin by oneskilled in the art of this field can be illustrated. Furthermore,commercially available products can be used as the vinyl-containingcompound. Specific examples of the vinyl-containing compound include DMSSeries, PDV Series, FMV Series, VDT Series, VMS Series, VTT Series andMTV Series, products of Gelest, Inc.: ME-91, a product of MomentivePerformance Materials; and dimethyldivinylsilane,diethylmethylvinylsilane, dimethylphenylvinylsilane,divinylmethylphenylsilane, methyltrivinylsilane, phenyltrivinylsilane,trimethylvinylsilane and triphenylvinylsilane that are vinyl-containingsilane coupling agents.

The hydrosilyl-containing compound B can be those commerciallyavailable. Specific examples of these include HMS Series, DMS Series,HES Series, HDP Series, HPM Series and HAM Series, products of Gelest,Inc.; and KF-99 and KF-9901, products of Shin-Etsu Chemical Co., Ltd.

In a preferred embodiment, neither the vinyl-containing compound A northe hydrosilyl-containing compound B contain condensable functionalgroups.

In another preferred embodiment of the invention, the curablepolyorganosiloxanes are obtained using a noble metal oxide as acatalyst. Specific examples of the noble metal oxide are oxides of Pt,Rh, Ru, Ir, Pd and Fe. For, for example, hydrosilylation reaction, PdO₂is more preferable because of its higher catalytic activity. Theseoxides can be used in solid granular form, and can be removed from thereaction by processes known to those of skill in the art, such asfiltration and centrifugation. Alternatively, such catalysts can bepresent as a fixed bed catalyst. Either way, the result is that such ahydrosilylation catalyst is not part of the curable polyorganosiloxanecomposition, and accordingly such a catalyst is not part of the finalcured product, as evident using more traditional processes.

The present invention relates to a thermally curable polyorganosiloxanesprepared via hydrosilation reaction of amethylhydrido-polydimethylsiloxane (providing SiH along the polymerbackbone) and high molecular weight vinyl polysiloxane (providingreactive C═C bonds) in the presence of a platinum catalyst. Thermalcuring of the elastomeric resin results in an optically clear, thermallystable and mechanically robust elastomeric matrix. The performance andthermal durability of these encapsulant materials is significantlyimproved when compared to other commercial silicone resins thus makingthe system suitable for LED encapsulant application as well as foraerospace industry.

FIG. 1 represents the general procedure for the preparation of thesesilicone-based encapsulant resins which involves thefunctionalization/modification of a methylhydrido-polydimethylsiloxane(H-PDMS). High molecular weight vinyl silanes are incorporated along thepolysiloxane backbone by hydrosilylation using a solid PtO₂ catalyst.The solid catalyst is removed simply by centrifugation or filtration.This catalyst-free, PDMS-based liquid resin is unique and different fromother conventional PDMS-based resins. See for example U.S. Pat. No.7,160,972 B2 that discloses a polysiloxane-based resin typicallyemploying hydrosilylation cure chemistry. Such resin type requires2-part systems, where part A contains the platinum catalyst togetherwith vinylsiloxane copolymer and part B is the hydridosiloxanecopolymer.

A critical advantage of this approach is the versatility in thestructure and functionality of various vinyl silanes that are and can beincorporated along the PDMS backbone. This multifunctional system isless susceptible to inhibition than chain-end functionalized systems.This enables a library of resins to be prepared with controllabledegrees of crosslinking, and thus offers a wide variety of physicalproperties. This process is also highly efficient and requires very lowmonomer concentrations to create the desired change in the molecularstructure and mechanical properties without the need for complicatedmulticomponent systems. The key point is simplicity and functionality. Acatalyst-free system eliminates problems that may arise due to unwantedside reactions between the components of an LED package (i.e. LED chip,phosphors, packaging cup, etc.). In addition, the one-pot nature of theformulation makes the system even more attractive.

FIG. 2 illustrates the molecular structures of the various highmolecular weight vinyl silanes investigated in this study. Results haveshown that the use of these high molecular weight vinyl silanes did notaffect their optical transparency and thermal stability but rathersignificantly improved and/or modified the stiffness, toughness andflexibility of the resin.

Uses of the Semiconductor Light-Emitting Device Members Made with thePolyorganosiloxanes of the Invention

The semiconductor light-emitting device member in the present inventionis not particularly limited in its use and can be used for variouspurposes including as a member (sealing compound) for sealing asemiconductor light-emitting device and the like. Among others, bycombining with phosphor particles and/or inorganic oxide particles, thesemiconductor light-emitting device member in the present invention cansuitably be used for specific purposes. The combined use with phosphorparticles is described below.

Combined Use with Phosphor Particles

The semiconductor light-emitting device member in the present inventioncan be used, for example, as a wavelength conversion member bydispersing a phosphor in the semiconductor light-emitting device memberfor molding inside a semiconductor light-emitting device cup or coatingas a thin film on an appropriate transparent support. One phosphor maybe used alone or two or more types of phosphors may be used in anarbitrary combination and ratio for example to make the light-emittingdevice, ‘White LED’.

Phosphor

Composition of the phosphor is not particularly limited, but it ispreferable to combine a crystalline matrix, for example, metallic oxidesuch as Y₂O₃ and Zn₂SiO₄, phosphate such as Ca₅(PO₄)₃Cl, or sulfide suchas ZnS, SrS, and CaS with ions of rare earth metal such as Ce, Pr, Nd,Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, and Yb or ions of metal such as Ag, Cu,Au, Al, Mn, and Sb as an activator or coactivator.

Preferable examples of the crystalline matrix include sulfide such as(Zn, Cd)S, SrGa₂S₄, SrS, and ZnS, oxysulfide such as Y₂O₂S, aluminatesuch as (Y, Gd)₃Al₅O₁₂, YAlO₃, BaMgAl₁₀O₁₇, (Ba, Sr)(Mg, Mn)Al₁₀O₁₇,(Ba, Sr, Ca)(Mg, Zn, Mn)Al₁₀O₁₇, BaAl₁₂O₁₉, CeMgAl₁₁O₁₉, (Ba, Sr,Mg)O.Al₂O₃, BaAl₂Si₂O₈, SrAl₂O₄, Sr₄Al₁₄O₂₅, and Y₃Al₅O₁₂, silicate suchas Y₂SiO₅ and Zn₂SiO₄, oxide such as SnO₂ and Y₂O₃, borate such asGdMgB₅O₁₀, (Y, Gd)BO₃, halophosphate such as Ca₁₀(PO₄)₆(F, Cl)₂ and (Sr,Ca, Ba, Mg)₁₀(PO₄)₆Cl₂ and phosphate such as Sr₂P₂O₇ and (La, Ce)PO₄.

However, the above crystalline matrix and the activator or coactivatorare not particularly limited in elemental composition and can partiallybe substituted by analogous elements, and a resultant phosphor can beused if it absorbs light in the near-ultraviolet to visible region andemits visible light.

More specifically, substances shown below can be used as a phosphor, butthese are only exemplary substances and phosphors that can be used inthe present invention are not limited to these. In the exemplificationshown below, phosphors whose structure is different only partially areshown in an abbreviated manner when appropriate. For example,“Y₂SiO₅:Ce³⁺”, “Y₂SiO₅:Tb³⁺”, and “Y₂SiO₅:Ce³⁺, Tb³⁺” are shown in aunifying manner as “Y₂SiO₅:Ce³⁺, Tb³⁺”, and “La₂O₂S:Eu”, “Y₂O₂S:Eu” and“(La, Y)₂O₂S:Eu” are shown in a unifying manner as “(La, Y)₂O₂S:Eu”. Anabbreviated location is delimited by a comma (,).

Red Phosphor

The range of concrete wavelengths of fluorescence emitted by a phosphorthat emits red fluorescence (hereinafter referred to as a “red phosphor”when appropriate) is exemplified as usually 570 nm or more, preferably580 nm or more, and usually 700 nm or less, preferably 680 nm or less.

Such red phosphors include a europium activation alkaline earth siliconnitride phosphor represented by (Mg, Ca, Sr, Ba)₂Si₅N₈:Eu and configuredby fracture particles having a red fracture surface to emit light in thered region and europium activation rare earth oxychalcogenide phosphorrepresented by (Y, La, Gd, Lu)₂O₂S:Eu and configured by grown particleshaving approximately a spherical shape as a regular crystal growth shapeto emit light in the red region.

Further, a phosphor containing oxynitride and/or oxysulfide containingat least one element selected from a group consisting of Ti, Zr, Hf, Nb,Ta, W, and Mo disclosed by Japanese Patent Application Laid-Open No.2004-300247 and containing an α-sialon structure in which part or all ofAl elements are substituted by the Ga elements can also be used in thepresent embodiment. Such a phosphor is a phosphor containing oxynitrideand/or oxysulfide.

As other red phosphors, an Eu activation oxysulfide phosphor such as(La, Y)₂O₂S:Eu, Eu activation oxide phosphor such as Y(V, P)O₄:Eu andY₂O₃:Eu; Eu, Mn activation silicate phosphor such as (Ba, Sr, Ca,Mg)₂SiO₄:Eu, Mn and (Ba, Mg)₂SiO₄:Eu, Mn; Eu activation sulfide phosphorsuch as (Ca, Sr)S:Eu, Eu activation aluminate phosphor such as YAlO₃:Eu,Eu activation silicate phosphor such as LiY₉(SiO₄)₆O₂:Eu,Ca₂Y₈(SiO₄)₆O₂:Eu, (Sr, Ba, Ca)₃SiO₅:Eu, and Sr₂BaSiO₅:Eu, Ce activationaluminate phosphor such as (Y, Gd)₃Al₅O₁₂:Ce and (Tb, Gd)₃Al₅O₁₂:Ce, Euactivation nitride phosphor such as (Ca, Sr, Ba)₂Si₅N₈:Eu, (Mg, Ca, Sr,Ba)SiN₂:Eu, and (Mg, Ca, Sr, Ba)AlSiN₃:Eu, Ce activation nitridephosphor such as (Mg, Ca, Sr, Ba)AlSiN₃:Ce; Eu, Mn activationhalophosphate phosphor such as (Sr, Ca, Ba, Mg)₁₀(PO₄)₆Cl₂:Eu, Mn; Eu,Mn activation silicate phosphor such as (Ba₃Mg)Si₂O₈:Eu, Mn and (Ba, Sr,Ca, Mg)₃(Zn, Mg)Si₂O₈:Eu, Mn; Mn activation germanide phosphor such as3.5MgO.0.5MgF₂.GeO₂:Mn, Eu activation oxynitride phosphor such as Euactivation α-sialon; Eu, Bi activation oxide phosphor such as (Gd, Y,Lu, La)₂O₃:Eu, Bi; Eu, Bi activation oxysulfide phosphor such as (Gd, Y,Lu, La)₂O₂S:Eu, Bi; Eu, Bi activation vanadate phosphor such as (Gd, Y,Lu, La)VO₄:Eu, Bi; Eu, Ce activation sulfide phosphor such as SrY₂S₄:Eu,Ce; Ce activation sulfide phosphor such as CaLa₂S₄:Ce; Eu, Mn activationphosphate phosphor such as (Ba, Sr, Ca)MgP₂O₇:Eu, Mn and (Sr, Ca, Ba,Mg, Zn)₂P₂O₇:Eu, Mn; Eu, Mo activation tungstate phosphor such as (Y,Lu)₂WO₆:Eu, Mo; Eu, Ce activation nitride phosphor such as (Ba, Sr,Ca)_(x)Si_(y)N_(z):Eu, Ce (x, y, and z are integers equal to 1 orgreater); Eu, Mn activation halophosphate phosphor such as (Ca, Sr, Ba,Mg)₁₀(PO₄)₆(F, Cl, Br, OH):Eu, Mn and Ce activation silicate phosphorsuch as ((Y, Lu, Gd, Tb)_(1−x)Sc_(x)Ce_(y))₂(Ca, Mg)_(1−r)(Mg,Zn)_(2+r)Si_(z−q)Ge_(q)O_(12+δ) can also be used.

Also as a red phosphor, a red organic phosphor comprised of rare earthelement ion complexes having anions such as β-diketonate, β-diketone,aromatic carboxylic acid, and Broensted acid as ligands, perylenepigment (for example,dibenzo{[f,f]-4,4′,7,7′-tetraphenyl}diindeno[1,2,3-cd:1′,2′,3′-lm]perylene),anthraquinone pigment, lake pigment, azo pigment, quinacridone pigment,anthracene pigment, isoindoline pigment, isoindolinone pigment,phthalocyanine pigment, triphenylmethane basic dye, indanthrone pigment,indophenol pigment, cyanine pigment, and dioxazine pigment can also beused.

Also, among red phosphors, those whose peak wavelength is 580 nm ormore, preferably 590 nm or more, and 620 nm or less, preferably 610 nmor less can be suitably used as an orange phosphor. Examples such orangephosphors include (Sr, Ba)₃SiO₅:Eu, (Sr, Mg)₃(PO₄)₂:Sn²⁺, andSrCaAlSiN₃:Eu.

Green Phosphor

The range of concrete wavelengths of fluorescence emitted by a phosphorthat emits green fluorescence (hereinafter referred to as a “greenphosphor” when appropriate) is exemplified as usually 490 nm or more,preferably 500 nm or more, and usually 570 nm or less, preferably 550 nmor less.

Such green phosphors include a europium activation alkaline earthsilicon oxynitride phosphor represented by (Mg, Ca, Sr, Ba)Si₂O₂N₂:Euand configured by fracture particles having a fracture surface to emitlight in the green region and europium activation alkaline earthsilicate phosphor represented by (Ba, Ca, Sr, Mg)₂SiO₄:Eu and configuredby fracture particles having a fracture surface to emit light in thegreen region.

As other green phosphors, an Eu activation aluminate phosphor such asSr₄Al₁₄O₂₅:Eu and (Ba, Sr, Ca)Al₂O₄:Eu, Eu activation silicate phosphorsuch as (Sr, Ba)Al₂Si₂O₈:Eu, (Ba, Mg)₂SiO₄:Eu, (Ba, Sr, Ca, Mg)₂SiO₄:Eu,and (Ba, Sr, Ca)₂(Mg, Zn)Si₂O₇:Eu; Ce, Tb activation silicate phosphorsuch as Y₂SiO₅:Ce, Tb, Eu activation boric acid phosphate phosphor suchas Sr₂P₂O₇—Sr₂B₂O₅:Eu, Eu activation halosilicate phosphor such asSr₂Si₃O₈-2SrCl₂:Eu, Mn activation silicate phosphor such as Zn₂SiO₄:Mn,Tb activation aluminate phosphor such as CeMgAl₁₁O₁₉:Tb and Y₃Al₅O₁₂:Tb,Tb activation silicate phosphor such as Ca₂Y₈(SiO₄)₆O₂:Tb andLa₃Ga₅SiO₁₄:Tb; Eu, Tb, Sm activation thiogallate phosphor such as (Sr,Ba, Ca)Ga₂S₄:Eu, Tb, Sm; Ce activation aluminate phosphor such as Y₃(Al,Ga)₅O₁₂:Ce and (Y, Ga, Tb, La, Sm, Pr, Lu)₃(Al, Ga)₅O₁₂:Ce, Ceactivation silicate phosphor such as Ca₃Sc₂Si₃O₁₂:Ce and Ca₃(Sc, Mg, Na,Li)₂Si₃O₁₂:Ce, Ce activation oxide phosphor such as CaSc₂O₄:Ce, Euactivation oxynitride phosphor such as SrSi₂O₂N₂:Eu, (Sr, Ba,Ca)Si₂O₂N₂:Eu, and Eu activation β-sialon and Eu activation α-sialon;Eu, Mn activation aluminate phosphor such as BaMgAl₁₀O₁₇:Eu, Mn; Euactivation aluminate phosphor such as SrAl₂O₄:Eu, Tb activationoxysulfide phosphor such as (La, Gd, Y)₂O₂S:Tb; Ce, Tb activationphosphate phosphor such as LaPO₄:Ce, Tb; sulfide phosphor such asZnS:Cu, Al and ZnS:Cu, Au, Al; Ce, Tb activation borate phosphor such as(Y, Ga, Lu, Sc, La)BO₃:Ce, Tb; Na₂Gd₂B₂O₇:Ce, Tb; and (Ba, Sr)₂(Ca, Mg,Zn)B₂O₆:K, Ce, Tb; Eu, Mn activation halosilicate phosphor such asCa₈Mg(SiO₄)₄Cl₂:Eu, Mn; Eu activation thioaluminate phosphor andthiogallate phosphor such as (Sr, Ca, Ba)(Al, Ga, In)₂S₄:Eu, and Eu, Mnactivation halosilicate phosphor such as (Ca, Sr)₈(Mg, Zn)(SiO₄)₄Cl₂:Eu,Mn can also be used.

Also, organic phosphors such as a pyridine-phthalimide condensationderivative, fluorescent dyes such as benzooxazinone, quinazolinone,coumarin, quinophthalone, and naphthalate imide, and terbium complexhaving hexylsalicylate as a ligand can be used as a green phosphor.

Blue Phosphor

The range of concrete wavelengths of fluorescence emitted by a phosphorthat emits blue fluorescence (hereinafter referred to as a “bluephosphor” when appropriate) is exemplified as usually 420 nm or more,preferably 440 nm or more, and usually 480 nm or less, preferably 470 nmor less.

Such blue phosphors include a europium activation barium-magnesiumaluminate phosphor represented by BaMgAl₁₀O₁₇:Eu and configured by grownparticles having approximately a hexagonal shape as a regular crystalgrowth shape to emit light in the blue region, europium activationcalcium halophosphate phosphor represented by (Ca, Sr, Ba)₅(PO₄)₃Cl:Euand configured by grown particles having approximately a spherical shapeas a regular crystal growth shape to emit light in the blue region,europium activation alkaline earth chloroborate phosphor represented by(Ca, Sr, Ba)₂B₅O₉Cl:Eu and configured by grown particles havingapproximately a cubic shape as a regular crystal growth shape to emitlight in the blue region, and europium activation alkaline earthaluminate phosphor represented by (Sr, Ca, Ba)Al₂O₄:Eu or (Sr, Ca,Ba)₄Al₁₄O₂₅:Eu and configured by fracture particles having a fractureshape to emit light in the blue region.

As other blue phosphors, an Sn activation phosphate phosphor such asSr₂P₂O₇:Sn, Eu activation aluminate phosphor such as Sr₄Al₁₄O₂₅:Eu,BaMgAl₁₀O₁₇:Eu, and BaAl₈O₁₃:Eu, Ce activation thiogallate phosphor suchas SrGa₂S₄:Ce and CaGa₂S₄:Ce, Eu activation aluminate phosphor such as(Ba, Sr, Ca)MgAl₁₀O₁₇:Eu and BaMgAl₁₀O₁₇:Eu, Tb, Sm; Eu, Mn activationaluminate phosphor such as (Ba, Sr, Ca)MgAl₁₀O₁₇:Eu, Mn; Eu activationhalophosphate phosphor such as (Sr, Ca, Ba, Mg)₁₀(PO₄)₆Cl₂:Eu and (Ba,Sr, Ca)₅(PO₄)₃(Cl, F, Br, OH):Eu, Mn, Sb; Eu activation silicatephosphor such as BaAl₂Si₂O₈:Eu and (Sr, Ba)₃MgSi₂O₈:Eu, Eu activationphosphate phosphor such as Sr₂P₂O₇:Eu, sulfide phosphor such as ZnS:Agand ZnS:Ag, Al; Ce activation silicate phosphor such as Y₂SiO₅:Ce,tungstate phosphor such as CaWO₄, Eu, Mn activation boric acid phosphatephosphor such as (Ba, Sr, Ca)BPO₅:Eu, Mn, (Sr, Ca)₁₀(PO₄)₆.nB₂O₃:Eu, and2SrO.0.84P₂O₅.0.16B₂O₃:Eu, and Eu activation halosilicate phosphor suchas Sr₂Si₃O₈.2SrCl₂:Eu can also be used.

Also, organic phosphors such as a fluorescent dye of naphthalate imide,benzooxazole, styryl, coumarin, pilarizon, and triazole compounds andthulium complex can be used as a blue phosphor.

One phosphor may be used alone or two or more types of phosphors may beused in an arbitrary combination and ratio.

A media particle diameter of these phosphor particles is notparticularly limited, but is usually 100 nm or more, preferably 2 μm ormore, and still preferably 5 μm or more, and usually 100 μm or less,preferably 50 μm or less, and still preferably 20 μm or less. Also, theshape of phosphor particles is not particularly limited as long asformation of semiconductor light-emitting device members is notaffected, for example, fluidity of a phosphor part formation liquid(liquid obtained by adding a phosphor to this invention's semiconductorlight-emitting device member formation liquid) is not affected.

In the present invention, the method of adding phosphor particles is notparticularly limited. If phosphor particles are in a good dispersionstate, it is sufficient only to post-mix phosphor particles into thesemiconductor light-emitting device member formation liquid. If phosphorparticles tend to aggregate, they can be mixed in advance into the rawmaterials before hydrosilylation.

The present invention is described further specifically by the Examples,but it should be understood that the invention is not limited to thefollowing Examples so far as the invention is not beyond its gist.

EXAMPLE 1 Functionalization of Polydimethylsiloxane (PDMS) with HighMolecular Weight Vinyl Silane (MT)

(a) with toluene: In a vial, charged with a stir bar, 1 g (20 wt. %) oftoluene was mixed with 3 g (58 wt. %) of H-PDMS (5-7% H, 65000 MW), 1.2g (22 wt. %) of MTV-112 (Gelest) vinyl silane and 1 mg (<200 ppm) ofPtO₂ (average diameter of particle is 20 μm: the smallest particle sizeis approximately 0.5 μm in diameter and the largest particle size isapproximately 50 μm in diameter) catalyst. The mixture was allowed toreact for 3 hours at 80° C. using an oil bath. The liquid resin was thencentrifuged for 10 minutes at 2000 rpm and decanted to remove the solidcatalyst. Toluene was removed by vacuum. The resin was then poured ontotared Teflon discs and cured at 150° C. for no less than 6 hours.

(b) no toluene: In a vial, charged with a stir bar, 3 g (72 wt. %) ofH-PDMS (5-7% H, 65000 MW) was mixed with 1.2 g (28 wt. %) of MTV-112(Gelest) vinyl silane and 1 mg (<200 ppm) of PtO₂ (Average diameter; 20μm (the smallest particle; ca. 0.5 μm diameter and the largest particle;ca. 50 μm diameter)) catalyst. The mixture was allowed to react for 2hours at 80° C. using an oil bath. The liquid resin was then centrifugedfor 10 minutes at 2000 rpm and decanted to remove the solid catalyst.The resin was then poured onto tared Teflon discs and cured at 150° C.for no less than 6 hours.

The following are the properties of the formulation:

Cure Processing PDMS + MT + PDMS + MT Characteristics toluene (notoluene) Shelf life at ambient 1 month 1 month temperature Cure time at150° C. 6 hours 6 hours Cured Properties Compatible with Compatible withphosphors phosphors Optical transparency 93% T 93% T at 400 nm Thermalstability 200° C. for 1 week 200° C. for 1 week Elastic modulus, MPa0.40 1.25 Ultimate Stress, MPa 0.56 0.35 Elongation at break 106% 30%

FIG. 3 shows optical transmittance of greater than 90% throughout the350 to 800 nm range for the formulation containing a high molecularweight silane (MT) along the polysiloxane backbone (obtained fromExample 1). Thermal stability of the cured resins was determined byageing the cured discs in a 200° C. oven for up to 7 days. Weight losswas observed to be less than 5% indicating minimal shrinkage andout-gassing of volatiles, thus no thermal degradation is occurring.There was no observed yellowing and the optical transmittance was stillgreater than 90% indicating good thermal durability and retention ofgood optical transparency. The material is also stable up to 300 nm,which also indicates resistance to UV. These properties make thesematerials highly suitable for encapsulation of LED devices.

FIG. 4 gives the isothermal stress-strain curves of the formulationcontaining a high molecular weight silane (MT) prepared with a solventand the same formulation prepared without a solvent as given in Example1 of this invention. The use of a small amount of solvent (20 wt. %)resulted to a softer (0.40 MPa modulus) and more flexible resin (106%elongation) while the formulation prepared without toluene was harder(1.25 MPa modulus) and more brittle (30% elongation).

EXAMPLE 2 Functionalization of Polydimethylsiloxane (PDMS) with HighMolecular Weight Vinyl Silane (VT)

In a vial, charged with a stir bar, 3 g (72 wt. %) of H-PDMS (5-7% H,65000 MW) was mixed with 1.2 g (28 wt. %) of VTT-106 (Gelest) and 1 mg(<200 ppm) of PtO₂ (average diameter of particle is 20 μm: the smallestparticle size is approximately 0.5 μm in diameter and the largestparticle size is approximately 50 μm in diameter) catalyst. The mixturewas allowed to react for 7 hours at 80° C. using an oil bath. The liquidresin was then centrifuged for 10 minutes at 2000 rpm and decanted toremove the solid catalyst. The resins were mixed until it becamecompletely homogeneous then poured onto tared Teflon discs and cured at150° C. for no less than 6 hours.

Cure Processing PDMS + VTT Characteristics Shelf life at ambient 2 monthtemperature Cure time at 150° C. 6 hours Cured Properties Compatiblewith phosphors Optical transparency 93% T at 400 nm Thermal stability200° C. for 1 week Elastic modulus, MPa 0.10 Ultimate Stress, MPa 0.68Elongation at break 323%

FIG. 5 compares the elastic properties of the formulation containinghigh molecular weight silanes given in Example 1 and Example 2 of thisinvention. Each silane had a different effect on the mechanicalproperties of the resin. The formulation containing VT silane producedquite soft (0.10 MPa modulus) and elastic (323% elongation) resin. Themechanical properties can be tuned simply by choosing the correspondinghigh molecular weight silane.

Results also demonstrated the compatibility of the silicone encapsulantresin with various inorganic phosphors. Depending on the viscosityand/or thixotropy of the resin, fillers/modifiers can be added to theresin.

The developed approach allows for the mechanical properties of theelastomeric resins to be varied and/or tuned to the desired stiffness,toughness and flexibility that best suit the specific application. Thesystem offers a range of material platforms that fulfill all of therequirements and function as advanced encapsulating materials for bothLED devices, as well as other emerging applications.

EXAMPLE 3

A stirring bar was placed in a round-bottom flask, and 3 g of H-PDMS(5-7% H, 65000 MW), 1.2 g of VTT-106 (Gelest) and 1 mg of PtO₂ (averagediameter of particle is 20% m: the smallest particle size isapproximately 0.5 μm in diameter and the largest particle size isapproximately 50 μm in diameter) catalyst were added to the flask. Thereaction was conducted at 80° C. for 12 hours with stirring. Theplatinum oxide catalyst was removed by centrifugal separation at 2,000rpm for 10 minutes yielding a curable polyorganosiloxane A of theinvention.

When Pt residual amount in the curable polyorganosiloxane A was measuredwith ICP emission spectral analysis, it was found to be less than 2 ppm(less than detection limit).

EXAMPLE 4

A stirring bar was placed in a round-bottom flask, and 1.0 g of toluene,3 g of H-PDMS (5-7% H, 65000 MW), 1.2 g of MTV-112(methyltri(vinyl-terminated polydimethylsiloxyl)silane (Gelest) and 1 mgof PtO₂ (average diameter of particle is 20 μm: the smallest particlesize is approximately 0.5 μm in diameter and the largest particle sizeis approximately 50 μm in diameter) catalyst were added to the flask.The reaction was conducted at 80° C. for 3 hours with stirring. Theplatinum oxide catalyst was removed by centrifugal separation at 2,000rpm for 10 minutes, and toluene was then removed under reduced pressureyielding a curable polyorganosiloxane B of the invention.

When Pt residual amount in the curable polyorganosiloxane B was measuredwith ICP emission spectral analysis, it was found to be less than 2 ppm(less than detection limit).

EXAMPLE 5

A stirring bar was placed in a round-bottom flask, and 2.0 g of toluene,8 g of H-PDMS (7-8% H, 80000 MW), 0.46 g of diethoxymethylvinylsilane,0.55 g of triethoxyvinylsilane and 1 mg of PtO₂ (average diameter ofparticle is 20 μm: the smallest particle size is approximately 0.5 μm indiameter and the largest particle size is approximately 50 μm indiameter) catalyst were added to the flask. Reaction was conducted at80° C. for 12 hours with stirring. The platinum oxide catalyst wasremoved by centrifugal separation at 2,000 rpm for 10 minutes, andtoluene was then removed under reduced pressure to obtain apolyorganosiloxane C.

EXAMPLE 6

A stirring bar was placed in a round-bottom flask, and 2.0 g of toluene,8 g of H-PDMS (5-7% H, 65000 MW), 0.46 g of diethoxymethylvinylsilane,0.55 g of triethoxyvinylsilane and 1 mg of PtO₂ (average diameter ofparticle is 20 μm: the smallest particle size is approximately 0.5 μm indiameter and the largest particle size is approximately 50 μm indiameter) catalyst were added to the flask. The reaction was conductedat 80° C. for 12 hours with stirring. The platinum oxide catalyst wasremoved by centrifugal separation at 2,000 rpm for 10 minutes, andtoluene was then removed under reduced pressure to obtain apolyorganosiloxane D.

Resins A, B, C and D prepared in Examples 3-6 were charged in a packageup to the uppermost level thereof, and cured at 150° C. for 7 hours. Thepackage used was a Cu substrate package with a dent of 8 mm diametercovered with 1 mm thick Ag plating.

The package was subjected to hygroscopic treatment under 85° C. and 85%RH condition for 12 hours, and then set on a 260° C. hot plate for 10seconds. Presence or absence of peeling between the resin and thepackage was visually checked using a microscope. The results are shownin FIG. 6, Table 1.

Generally speaking, a linear polyorganosiloxane without any condensablefunctional group like alkoxysilyl group, does not become an elasticresin merely by heating. However, the curable crosslinkedpolyorganosiloxane of the invention becomes an elastic resin simply byheating through thermal equilibration of siloxane bond (decompositionand rebonding reaction of a siloxane bond). In particular, where a highmolecular weight linear polyorganosiloxane is used as a raw material, amolecular weight is increased by small numbers of rebondings and/orcrosslinking reaction, and as a result, curing is liable to occur.

From the results, (See FIG. 6) the resins A and B of the invention havestrong adhesion to a metal package as compared with the resins C and Dthat have a condensable functional group and this makes resins A and Bsuitable for an encapsulating material of LED. The reason for thisphenomenon is now under investigation, but hydroxyl group generatedduring the thermal equilibrium reaction most likely plays an importantrole at the interface of the resin and the metal package.

EXAMPLE 7

4 parts by weight of silica fine particles (RX200, a product of NipponAerosil Co., Ltd.), 16.2 parts by weight of blue phosphorBa_(0.7)Eu_(0.3)MgAl₁₀O₁₇ (particle diameter: 15 μm; hereinafterreferred to as “BAM”), 1.5 parts by weight of green phosphorBa_(0.75)Sr_(0.25)SiO₄:Eu (particle diameter: 16 μm; hereinafterreferred to as “BSS”) and 1.1 parts by weight of red phosphorSr_(0.8)Ca_(0.2)AlSiN:Eu (particle diameter: 12 μm; hereinafter referredto as “SCASN”) were mixed with 100 parts by weight of the resin Aobtained in Example 1, and the resulting mixture was kneaded with astirring device (AR-100), a product of THINKY, for 3 minutes to make acurable composition E of the invention.

EXAMPLE 8

4 parts by weight of silica fine particles (RX200, a product of NipponAerosil Co., Ltd.), 16.2 parts by weight of blue phosphor BAM, 1.5 partsby weight of green phosphor BSS and 1.1 parts by weight of red phosphorSCASN were mixed with 100 parts by weight of the resin B obtained inExample 2, and the resulting mixture was kneaded with a stirring device(AR-100), a product of THINKY, for 3 minutes to make a curablecomposition F of the invention.

EXAMPLE 9

6 parts by weight of silica fine particles (RX200, a product of NipponAerosil Co., Ltd.), 16.5 parts by weight of blue phosphor BAM, 1.5 partsby weight of green phosphor BSS and 1.1 parts by weight of red phosphorSCASN were mixed with 100 parts by weight of the commercially availableaddition-curing silicone resin (KER2500, a product of Shin-Etsu ChemicalCo., Ltd.), and the resulting mixture was kneaded with a stirring device(AR-100), a product of THINKY, for 3 minutes to make a curablecomposition G of the invention.

The curable compositions (phosphor pastes) E, F and G made in Examples7-9 were used to prepare white LED devices of near ultravioletexcitation. The LED package depicted in the Example 6 with alight-emitting diode having an emission wavelength of 403 nm (C405XB900,a product of Cree Inc.) wire-bonded to the bottom center of the packagewas filled up with each of the phosphor pastes E, F and G. Packages withE and F were cured at 150° C. for 7 hours, and that with G was cured at100° C. for 1 hour, and then cured at 150° C. for 5 hours.

350 mA current was passed through the white LED obtained above at 25° C.to measure the total light flux, and 350 mA current was then passedthrough the same in an atmosphere of 85° C. and 85% RH to conductaccelerated deterioration test for 500 hours. Thereafter, 350 mA currentwas again passed through the white LED at 25° C. to measure the totallight flux after the test, and its retention rate was calculated. Theresults are shown in FIG. 7, Table 2.

As is apparent from above, when the curable composition of the inventionis used, white LEDs have less decrease of light emission intensity andhigher reliability than LEDs with conventional silicone resins inComparative Example 5 and 6.

The reason for this phenomena is considered to be that a conventionalsilicone resin with some metal catalyst turn its color under the strongnear ultraviolet light irradiation from LED and high temperature,whereas the curable composition of the invention without metal catalyststays colorless and transparent under these harsh condition.

The present application has been described using specific aspects of theinvention. Additional descriptions of semiconductor light emittingdevices, and LEDs in particular, as well as manufacturing methodstherefore, and industrial applicability can be found in detail inEuropean Patent No. WO2006090804 published Aug. 31, 2006, and alsopublished as EP1854831 (A1), the specification of which is herebyincorporated herein in its entirety.

REFERENCES

-   1. US Patent Application Publication No. 2004/0063840-   2. WIPO Publication No. WO2005/085303-   3. Japanese Patent Document: JP-A-2002-203989-   4. Japanese Patent Document: JP-A-2004-356506-   5. U.S. Pat. No. 5,648,687-   6. WIPO Publication No. WO2006/055456-   7. U.S. Pat. No. 7,160,972-   8. U.S. Pat. No. 6,204,523-   9. U.S. Pat. No. 6,590,235

1) A curable polyorganosiloxane comprising a compound represented by thefollowing formula in an amount of 50% by weight or more, characterizedin that said polyorganosiloxane cures, substantially in the absence of ahydrosilylation catalyst:

wherein R₁, to R₁₀ each independently represent a group selected fromhydride, alkyl, alkenyl, aryl and non-condensable silyl group, and m andn each are an integer of 0 or more. 2) The curable polyorganosiloxane ofclaim 1, that can be cured either by heating at a temperature of 80° C.or higher for an overall heating temperature of 1 hour or more. 3) Thecurable polyorganosiloxane of claim 1, obtained by reacting avinyl-containing compound (A) and a hydrosilyl-containing compound (B),wherein said compounds A and B are represented by the following generalformulae:

wherein R₁₁ is a group selected from alkyl, aryl and non-condensablesilyl group;

wherein R₁₂ to R₂₀ each independently represent a group selected fromhydride, alkyl, alkenyl, aryl and non-condensable silyl group, and m andn each are an integer of 0 or more. 4) The curable polyorganosiloxane ofclaim 1, which can be obtained using a noble metal oxide as a catalyst.5) The curable polyorganosiloxane of claim 3, wherein thevinyl-containing compound (A) and/or the hydroxyl-containing compound(B) have a weight average molecular weight of 3,000 or more obtained bymeasuring with gel permeation chromatography using a polystyrenestandard material in calibration curve measurement. 6) A curablecomposition comprising the curable polyorganosiloxane of claim
 3. 7) Thecurable composition in claim 5, which does not substantially contain anoble metal component. 8) A silicone member obtained by curing thecurable composition in claim
 6. 9) A semiconductor luminescent devicecomprising the silicone member in claim
 7. 10) A member for aerospaceindustry comprising the silicone member in claim 7.